An automotive closure, such as a door for an automobile passenger compartment, is hinged to swing between open and closed positions and conventionally includes a door latch that is housed between inner and outer panels of the door. The door latch functions in a well known manner to latch the door when it is closed and to lock the door in the closed position or to unlock and unlatch the door so that the door can be opened manually.
The door latch is operated remotely from the exterior of the automobile by two distinct operators--a key cylinder that controls the locking mechanism and an outside door handle or push button that controls the latching mechanism.
The door latch is also operated remotely from inside the passenger compartment by two distinct operators--a sill button that controls the locking mechanism and an inside door handle that controls the latching mechanism. Vehicle door latches for upscale automobiles may also include power door locks in which the locking mechanism is motor driven and/or a keyless entry in which a key fob transmitter sends a signal to a receiver in the vehicle to operate a motor driven locking mechanism.
U.S. Pat. No. 5,277,461 granted to Thomas A. Dzurko et al on Jan. 11, 1997 for a vehicle door latch, which is hereby incorporated in this patent specification by reference, discloses a typical door latch of the above-noted type. The door latch disclosed in the Dzurko '461 patent includes an unlatching lever 60 that is pivotally mounted on a stud 28 that is secured to a metal back plate 16 and a metal face plate 14 at opposite ends. Unlatching lever 60 is operated to unlatch the vehicle door by an inside handle lever 56 that is connected by a suitable linkage for rotation by an inside door handle (not shown). Unlatching lever 60 is also operated by an outside handle lever 50 that is connected by suitable linkage for rotation by an outside door handle (not shown).
The Dzurko door latch also includes a locking lever 40 that is pivotally mounted on stud 28. Locking lever 40 is operated by an inside locking lever 80 that is pivotally mounted on the flange of the metal face plate 14 near the inside handle lever 56. The inside locking lever 80 is operated by an inside sill button or lock slide through a suitable linkage (not shown). Locking lever 40 is also operated by an outside locking lever 82 that is operated by a key lock cylinder through a suitable linkage (not shown). In some instances, for example in upscale automobiles, locking lever 40 is also power operated by a remotely controlled linear electric motor or the like in a well known manner (not shown).
The door latch disclosed in the Dzurko '461 patent is unlocked and unlatched in the following sequence. First, the locking lever 40 is moved to the unlocked position by the inside locking lever 80, the outside locking lever 82 or, in the instance of a vehicle equipped with power door locks, a remotely-controlled motor. This moves the intermittent lever 34 to the unlocked position. After the door latch is unlocked, the door latch is unlatched by moving the unlatching lever 60 via inside handle lever 56 or outside handle lever 50 to the unlatched position pulling intermittent lever 44 and detent 32 down to unlatch the door lock. The vehicle door then may be pushed or pulled open manually.
Door latches of the type disclosed in the Dzurko '461 patent have been used successfully by General Motors Corporation for many years.
However, there are instances where driver or passenger impatience initiates the unlatching operation prematurely reversing the normal sequence of unlocking and then unlatching the door lock to enter or exit a locked vehicle. Of course, the door lock cannot be unlatched when in the locked condition. However, when the unlatching lever 60 moves to the unlatching position, the unlatching lever 60 blocks the intermittent lever 34 and prevents movement of the locking lever 40 to the unlocked position resulting in an impasse where the door lock cannot be unlocked or unlatched.